Sofa



FIG. 1 is a front perspective view of a sofa in accordance with the new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a back perspective view thereof; and,

FIG. 4 is a side elevation view, an opposite side elevation view being a mirror image thereof.

The dot-dashed lines shown in the drawings are for illustrative purposes only and form no part of the claimed design.

Broken lines on the sofa are understood to represent stitching. 

The ornamental design for a sofa, as shown and described. 